The present invention relates to data port switching circuits in mobile data terminals and more particularly to a programmable data port interface adapter.
There are many applications in which it is desirable for a computer type device to be able to communicate with a variety of external devices. For example, in a public mass transit environment, it would be advantageous for a mobile data terminal having data ports for connecting with RS-232 peripheral devices (e.g., printers, bar code readers, etc.) to be able to also accommodate input from J1708 peripheral devices (e.g., ADA Annunciator systems or passenger counting systems). Typical prior data terminal systems having RS-232 ports do not accommodate J1708 devices. Further, if connection to both J1708 and RS-232 ports is desired, dedicated ports for each type of device is typically required which are mutually exclusive to the other type of data port. Devices designed for RS-232 ports would require costly and time consuming hardware configurations to accommodate J1708 ports. Further, standard hardware switching circuits would typically add to the complexity and cost of the mobile data terminal.
It is therefore an object of the invention to provide a programmable data port interface adapter allowing for one type of data port to be seamlessly converted to another type of data port in an interface adapter system.
It is another object of the present invention to provide a mobile data terminal having modifiable data ports without requiring hardware modifications of the data terminal.
It is yet a further object of the invention to provide an interface adapter having a reconfigurable data port that dynamically adjusts the data port type according to the attached peripheral device.